Added tags query

model/story/tag.go

@@ -1,5 +1,12 @@
 package story
 
+import (
+	"sort"
+	"strings"
+
+	"github.com/globalsign/mgo/bson"
+)
+
 // A Tag associates a story with other content, like other stories, logs and more.
 type Tag struct {
 	Kind string `bson:"kind"`
@@ -10,3 +17,20 @@ type Tag struct {
 func (tag *Tag) Equal(other Tag) bool {
 	return tag.Kind == other.Kind && tag.Name == other.Name
 }
+
+// ListTags lists all tags
+func ListTags() ([]Tag, error) {
+	tags := make([]Tag, 0, 64)
+	err := storyCollection.Find(bson.M{"tags": bson.M{"$ne": nil}}).Distinct("tags", &tags)
+
+	sort.Slice(tags, func(i, j int) bool {
+		kindCmp := strings.Compare(tags[i].Kind, tags[j].Kind)
+		if kindCmp != 0 {
+			return kindCmp < 0
+		}
+
+		return strings.Compare(tags[i].Name, tags[j].Name) < 0
+	})
+
+	return tags, err
+}